Control valve

ABSTRACT

A control valve for use with a hydraulic system in which a variable displacement pump is controlled by the pressure drop from the inlet port to the work port of the control valve includes an improved logic system. This logic system provides flow reversible fluid communication between a control port and either of two work ports in the control valve when either work port is connected to the inlet port; and it provides an attenuation path from the control port to an exhaust port when neither work port is connected to the inlet port.

United States Patent 1191 Miller July 3, 1973 [54] CONTROL VALVE 3.631.890 1/1972 McMillen 137/596.13

[75] Inventor: Wendell E. Miller, Warsaw, 1nd. I Primary Examiner Hemy T Klinksiek 1 gn m rg-Wa n r rpor i n. Chi g Assistant Examiner-Robert J. Miller 111. Att0rney Donald W. Banner, Henry S. Layton et a].

i 2 F 'l l 1971 l 2] y 26 1571 ABSTRACT [21] Appl l66l55 A control valve for use with a hydraulic system in which a variable displacement pump is controlled by [52] US. Cl. 137/625.68, 60/52 VS h pressure p f h inl p rt to he work port [51] Int. Cl. F15! 15/18, F16d 31/06, F041 1/02 of the control valve includes an improved logic system. [58] Field of Search l37/625.68, 596.13, i gic ys em pr vide flow reversible fluid commu- 137/1 15; 60/52 VS nication between a control port and either of two work ports in the control valve when either work port is con- [56] References Cit d nected to the inlet port; and it provides an attenuation UNITED STATES PATENTS path from the control port to an exhaust port when nei- 3,486,334 12/1969 Miller 60/52 vs the? work port connected to the 3,602,243 8/1971 Holt et a1 137/115 11 Claims, 3 Drawing Figures CONTROL VALVE BACKGROUND OF THE INVENTION The present invention provides an improved control valve for use with load responsive systems such as is described in U.S. Pat. No. 3,526,247 of common assignee. The present invention offers a more compact and less costly valve than heretofore known. Herein is disclosed a valve for use in a load responsive system which is shorter in length, has less lands, and can be produced by a more economical method. The present valve has the logic built into a bore in the spool portion thus eliminating the extra bore, and the cost thereof, from the body of the valve.

SUMMARY OF THE INVENTION The improved control valve includes a logic system that is effective to select the load actuating pressure from either work port for use as a control signal pressure. This control signal pressure may be used to control the effective output of a fixed or variable pump, as described in U.S. Pat. No. 3,526,247. The improved control valve may be used in place of the control valve disclosed in co-pending application Ser. No. 757,960, now U.S. Pat. No. 3,592,216, and may be used with the logic system shown in co-pending application Ser. No. 757,961 now abandoned.

The logic passage means comprising a logic system of the present invention includes a longitudinal passage in the valve spool and logic ports which intercept the longitudinal passage and selectively communicate wit work and exhaust ports.

One form of the invention includes commutator ports which prevent fluid from flowing from one logic port to the other logic port when one logic port is connected to a work port and the other logic port is connected to the exhaust port.

A variation of the invention includes a three-port IN THE DRAWINGS FIG. 1 shows a cross-sectional. view of a four-way control valve of the present invention in which commutator ports are used to prevent flow of fluid from one logic port to another;

FIG. 2 is a three-way valve spool for the FIG. 1 configuration.

FIG. 3 is a four-way valve spool for the FIG. 1 configuration; and this valve spool utilizes a three-port logic valve to prevent flow of fluid from one logic port to another.

DESCRIPTION OF THE DRAWINGS The FIG. 1 configuration includes a pump and sump 11 as comprising a source of fluid pressure, a sensor valve 12, a control-valve l3, and a fluid motor 14.

Pump 10 includes a displacement control mechanism 15 which includes stroke piston 16, spring 17, and destroke piston 18. Sensor valve 12 (which is symbolically illustrated) includes neutral position 20, displacement increasing position 21, displacement decreasing position 22, displacement increasing operator 23, displacement decreasing operator 24, and pressure differential spring 25. Motor 14 includes motor ports 26 and 27 and piston 28.

Control valve 13 includes valve body 30 having exhaust ports 31a and 31b being connected to common exhaust port 32 by loop 33, work ports 34a and 34b, an input port means including input ports 35a and 35b being connected to common input port 36 by loop 37, control port 38, and spool bore 39.

Valve spool 42 is slidably fitted in spool bore 39 and includes lands 43a and 43b, land 44, reduced diamter portions 45a and 45b and timing notch 46. Body 30 of control valve 13 includes notch which may be used as a design alternative to timing notch 46 of valve spool 42.

Valve spool 42 also includes a logic port means consisting of logic ports 47a and 47b, longitudinal logic passages 48a and 48b, and commutator ports 49a and 49b.

In usual design practice, logic ports 47a and 47b, commutator ports 49a and 49b, and timing notches 40 or 46 would be made in pairs spaced on opposite sides of the valve spool and spool bore in order to provide radial pressure balance. That is, a typical valve spool would include two logic ports spaced at 90 and 270.

Referring again to FIG. 1, valve 13 is shown with valve spool 42 in its neutral position; and inlet ports 35a and 35b are shown as being isolated from work ports 34a and 34b and from exhaust ports 31a and 31b. However, for some applications it is desirable to provide a communication path between a work port and an exhaust port when the valve spool is in the neutral position. Reduced diameter portion 45b can be lengthened to provide communication between work port 34b and exhaust port 31b if this feature is desired.

With valve spool 42 in its neutral position, as shown, dual control signal attenuating or dissipation paths are provided that connect control port 38 to exhaust ports 31a and 31b via commutator ports 49a and 49b, longitudinal passages 48a and 48b, and logic ports 47a and 47b. Thus any control signal pressure in operator 23 and in control signal conduit 52 is attenuated by fluid flow to sump 11a via conduit 53.

The attenuation or dissipation of control signal pressure in operator 23 allows sensor valve 12 to be shifted to displacement decreasing position 22 by operator 24 with only the force of spring 25 to oppose operator 24. If the force of spring 25 is overcome with one hundred psi in operator 24, then a pump pressure of psi in conduits 54 will move sensor valve 12 to position 22,

fluid will be returned from stroke piston 16 to sump 1 lb via conduits 55 and 56 and path 57, pump pressure will be conducted to destroke piston 18 via conduit 54a, and the displacement will just maintain 100 psi in conduit 54 and operator 24.

The displacement of pump 10 will be reduced to maintain lOOpsi-at standby conditions without regard to the flow path that is required to maintain the 100 psi. With the valve as shown in FIG. 1, practically no displacement is required to maintain the 100 psi.

Referring again to FlG. 1, when valve spool 42 is moved to the right to a first operating position, inlet port 35b is connected to work port 34b and to motor port 26 via reduced diameter portion 45b and conduit 60, and motor port 27 and work port 34a are connected to exhaust port 31a and sump 11a via reduced diameter portion 450 and notch 40.

Means to occlude the attenuation or dissipation path are provided by movement of valve spool 42 to the right. One attenuation path is occluded by moving commutator port 49a away from communication with control port 38. The other attenuation or dissipation path is occluded by moving logic port 47b away from communication with exhaust port 31b. Movement of valve spool 42 to the right is also effective to supply the working pressure from work port 3412 and motor port 26 to displacement increasing operator 23 by moving logic port 47b into communication with work port 34b thereby providing a fluid path from work port 34b to control port 38 which includes longitudinal passage 48b and commutator port 49b.

With valve spool 42 moved to the right and the connections made as enumerated, sensor valve 12 is controlled by the difference in fluid pressures in operators 23 and 24 and by spring 25. The difference in fluid pressures that are applied to operators 23 and 24 is dependent upon the flow and pressure drop from inlet port 35b to work port 34b; because full pump pressure is applied to operator 24, but the pressure applied to operator 23 is equal to the load pressure in work port 34b.

Valve spool 42 may be positioned at points between the neutral position, as shown, and the first operating position, to control the fluid restriction between inlet port 35b and work port 34b. With any given fluid restriction between inlet port 35b and work port 34b, sensor valve 12 will respond to the pressure differential caused by flow from inlet port to work port; and sensor valve 12 will make fluid connections between stroke piston 16 and conduit 54 or sump 11b to adjust the displacement of pump until the fluid flow from inlet port 35b to work port 34b provides the pressure differential which balances the force of spring 25; and then sensor valve 12 will be moved to neutral position to maintain a constant displacement of pump 10.

A pressure drop from inlet port 35a to motor port 34a that is too low will allow spring to move sensor valve 12 to position 21, fluid from conduit 54b will be applied to stroke piston 16 via path 61 and conduit 55, the displacement of pump 10 will be increased, fluid flow to work port 34b will be increased, the pressure drop from inlet port 35b to work port 34b will be increased, the difference in pressure in operators 23 and 24 will be increased, and sensor valve 12 will be moved to neutral position 20.

A pressure drop from inlet port 35 a to work port 34a that is too high will result in a decrease in pump displacement because operator 24 will be able to move sensor valve 12 to position 22 thereby releasing fluid from stroke piston 16 to sump llb via path 57 and allowing destroke piston 18 to overcome stroke piston 16 and spring 17.

If, while valve spool 42 is to the right, to the first operating position, the load being applied to motor 14 is decreased, the load actuating pressure in work port 34b is decreased, the excess fluid in operator 23 and control port 38 is delivered to work port 34b and to motor port 26. Thus the logic system is flow reversible between work port and control port.

Referring again to FIG. 1, operation with valve spool 42 moved to the left to a second operating position is similar to that which has been described. Instead of input port 35b being connected to work port 34b, input port 35a is connected to work port 340. The logic system functions in the same manner as described above using the ports indicated by the letter a.

Referring now to FIG. 2, valve spool of FIG. 2 may be used in valve body 30 of FIG. 1 to provide a three-way valve. In this case, work port 34b is inoperative, one logic passage including logic port 47a and commutator port 49a is eliminated, and commutator port 49b is replaced by collector port 71 which is always in communication with control port 38. Thus collector 71 and logic port 47b communicate control port 38 to exhaust port 31b when valve spool 70 is in a neutral position. When valve spool 70 is moved to the right (its only working position), the logic system functions as previously described.

Referring now to FIG. 3, valve spool 75 includes a fluid actuated three-port logic valve 76. Logic valve 76 includes first control signal input port 77a, second control signal input port 77b, output port 78 and ball or shuttle 79.

Valve spool 75 includes first spool portion 80 and second spool portion 81 which may be copper brazed at joint 82; or they may be connected by any suitable process. A preferred design includes copper brazing in a controlled atmosphere to control oxidation and the use of a stainless steel ball.

First spool portion 80 includes land 43a, logic port 47a, reduced diameter portion 45a, land 83, longitudinal passage 84, bore 85, counterbore 86, output port 78, and input port 770. Second spool portion 81 includes land 43b, logic port 47b, notch 46, valving face 87b, reduced diameter portion 88, longitudinal passage 89, and input port 77b.

Referring now to FIGS. 1 and 3, valve spool 75 of FIG. 3 may be used in valve body 30 of FIG. 1; and the functioning of valve spool 75 is the same as that of valve spool 42 except for the logic functions.

When valve spool 75 is in a neutral position, a control signal attenuating or dissipation path is provided from control port 38 to common exhaust port 32 via output port 78, bore 85, one of the control signal input ports 77a or 77b, longitudinal passage 84 or 89, one of the logic ports 47a or 47b, and one of the exhaust ports 31a or 311:. One of these paths will be open because ball 79 cannot simultaneously seat against input ports 77a and 77b.

When valve spool 75 is moved to the right, logic port 47b is moved from communication with exhaust port 31b, into communication with notch 41 and work port 34b, the load actuating or working pressure in work port 34b is communicated to longitudinal passage 89 and ball 79 is seated in the input port 770 thereby preventing the control signal pressure in control port 38 and output port 78 from being attenuated by flowing to exhaust port 31a via longitudinal passage 84 and logic port 470, and a reversible flow fluid communication path is established between work port 34b and control port 38. Thus it can be seen that logic valve 76 performs, by fluid actuation, the same function that commutator ports 49a and 49b perform by movement of valve spool 42.

The timing of the logic functions of valve spools 42, 70 and 75 may be controlled in relation to the timing of the other control valve functions to achieve special advantage. For instance, referring to FIG. 1, blocking both attenuation paths and communicating logic port 47b to work port 34b before opening inlet port 35b to work port 34b will result in pre-pressurizing pump and in decreasing the response time of the system.

Timing of the logic system to achieve pre-pressurization may be achieved by controlling the longitudinal length and relative locations of logic ports 47a and 47b of all three valve spools and by controlling the longitudinal length and relative locations of commutator ports 49a and 49b of the FIG. 1 configuration.

A notch 41 may be used in spool bore 39 of body 30 to control timing between logic port 47b and work port 34b and also to determine the overlap/underlap condition between the longitudinal lengths of logic port 47b and land 50.

In addition, a timing notch 46 may be used on spools 42, 70 and 75, or a notch 40 may be used in valve body 30 to reduce the spool travel that is required to connect work ports 34a and 34b and exhaust ports 31 a and 31b below that which would otherwise be required because of the edge margin material that is required between logic ports 47a and 47b and valving faces 87a and 87b.

Having described representative configurations of my invention, other variations being apparent to those who are skilled in the art, I claim:

1. A control valve having a body which includes an inlet port, a work port, an exhaust port, a control port and a spool bore intersecting all of said ports; a valve spool being slidably fitted into said spool bore and being movable from a neutral position wherein said inlet port is effectively isolated from said work port and said exhaust port, to a first operating position wherein said work port is connected to said inlet port, and to a second operating position wherein said work port is connected to said exhaust port; and logic passage means in said valve spool, said logic passage means being adapted to communicate said control port with said work port when said work port is connected with said inlet port and to communicate said control port with said exhaust port when said work port is isolated from said inlet port; said logic passage means includes a longitudinal passage in said valve spool commutator port means intercepting said longitudinal passage and being adapted to communicate with said control port, and logic port means intercepting said longitudinal passage and being adapted to selectively communicate with said work port and said exhaust port; said valve spool includes lands and reduced diameter portions; said logic port means is in one of said lands; said valve spool further includes a first valving face consisting of the surface area between said one land and the adjacent one of said reduced diameter portions; said spool bore includes a second valving face consisting ofa portion of said exhaust port which is adjacent to said work port; and one of said valving faces includes notch means being adapted to establish initial communication between said work port and said exhaust port when said valve spool is moved toward said second operating position.

2. A control valve having a body which includes inlet port means, first and second work ports, first andsecond exhaust ports, a control port, and a spool bore intersecting all of said ports;

a valve spool being slidably fitted into said spool bore and being movable from a neutral position wherein said inlet port means is isolated from both of said work ports and both of said exhaust ports, to a first operating position wherein said first work port is connected to said inlet port means and said second work port is connected to said second exhaust port, and to a second operating position wherein said second work port is connected to said inlet port means and said first work port is connected to said first exhaust port;

and logic passage means in said valve spool, said logic passage means being adapted to communicate said control port with at least one of said exhaust ports when said valve spool is in said neutral position, to communicate said control port with said first work port when said first work port is connected to said inlet port means, and to communicate said control port with said second work port when said second work port is connected to said inlet port mean.

3. a control valve as claimed in claim 2 in which said logic passage means includes longitudinal passage means in said valve spool, commutator 'port means intercepting said longitudinal passage means and being adapted to communicate with said control port, a first logic port intercepting said longitudinal passage means and being adapted to selectively communicate with said first work port and said first exhaust port, and a second logic port intercepting said longitudinal passage means being adapted to selectively communicate with said second work port and said second exhaust port.

4. A control valve as claimed in claim 3 which includes occluder means cooperating with said longitudinal passage means and said control port and being adapted to prevent fluid from flowing from one of said logic ports to the other of said logic ports when one of said logic ports is communicated with said inlet port means and the other of said logic ports is communicated with one of said exhaust ports.

5. A control valve as claimed in claim 4 in which said longitudinal passage means includes first and second longitudinal passages;

one of said logic ports intercepts each of said longitudinal passages;

said commutator port means includes a first commutator port intercepting said first longitudinal passage and a second commutator port intercepting said second longitudinal passage;

and said commutator ports cooperate with said control port and adjacent portions of said spool bore to comprise said occluder means.

6. A control valve as claimed in claim 5 in which movement of said valve spool from said neutral position toward one of said operating positions is effective to occlude communication between one of said com mutator ports and said control port before said inlet port means is connected with one of said work ports.

7. A control valve as claimed in claim 5 in which movement of said valve spool from said neutral position toward one of said operating positions is effective to occlude communication between one of said logic ports and one of said exhaust ports before said inlet port means is connected with one of said work ports.

8. A control valve as claimed in claim 4 in which said occluder means includes fiuid actuated valve means being adapted to communicate with said control port and with both of said longitudinal passages.

9. A control valve as claimed in claim 8 in which said fluid actuated valve is comprised of a three-port logic valve having a first port in communication with said control port, a second port in communication with one of said logic ports, and a third port in communication with the other of said control ports;

and said logic valve is effective to provide reversible flow fluid communication between said first port and one or the other of said ports at all times.

10. A control valve as claimed in claim 4 in which movement of said valve spool from said neutral position toward one of said operating positions is effective between said inlet ports. 

1. A control valve having a body which includes an inlet port, a work port, an exhaust port, a control port and a spool bore intersecting all of said ports; a valve spool being slidably fitted into said spool bore and being movable from a neutral position wherein said inlet port is effectively isolated from said work port and said exhaust port, to a first operating position wherein said work port is connected to said inlet port, and to a second operating position wherein said work port is connected to said exhaust port; and logic passage means in said valve spool, said logic passage means being adapted to communicate said control port with said work port when said work port is connected with said inlet port and to communicate said control port with said exhaust port when said work port is isolated from said inlet port; said logic passage means includes a longitudinal passage in said valve spool commutator port means intercepting said longitudinal passage and being adapted to communicate with said control port, and logic port means intercepting said longitudinal passage and being adapted to selectively communicate with said work port and said exhaust port; said valve spool includes lands and reduced diameter portions; said logic port means is in one of said lands; said valve spool further includes a first valving face consisting of the surface area between said one land and the adjacent one of said reduced diameter portions; said spool bore includes a second valving face consisting of a portion of said exhaust port which is adjacent to said work port; and one of said valving faces includes notch means being adapted to establish initial communication between said work port and said exhaust port when said valve spool is moved toward said second operating position.
 2. A control valve having a body which includes inlet port means, first and second work ports, first and second exhaust ports, a control port, and a spool bore intersecting all of said ports; a valve spool being slidably fitted into said spool bore and being movable from a neutral position wherein said inlet port means is isolated from both of said work ports and both of said exhaust ports, to a first operating position wherein said first work port is connected to said inlet port means and said second work port is connected to said second exhaust port, and to a second operating position wherein said second work port is connected to said inlet port means and said first work port is connected to said first exhaust port; and logic passage means in said valve spool, said logic passage means being adapted to communicate said control port with at least one of said exhaust ports when said valve spool is in said neutral position, to communicate said control port with said first work port when said first work port is connected to said inlet port means, and to communicate said control port with said second work port when said second work port is connected to said inlet port mean.
 3. A control valve as claimed in claim 2 in which said logic passage means includes longitudinal passage means in said valve spool, commutator port means intercepting said longitudinal passage means and being adapted to communicate with said control port, a first logic port intercepting said longitudinal passage means and being adapted to selectively communicate with said first work port and said first exhaust port, and a second logic port intercepting said longitudinal passage means being adapted to selectively communicate with said seCond work port and said second exhaust port.
 4. A control valve as claimed in claim 3 which includes occluder means cooperating with said longitudinal passage means and said control port and being adapted to prevent fluid from flowing from one of said logic ports to the other of said logic ports when one of said logic ports is communicated with said inlet port means and the other of said logic ports is communicated with one of said exhaust ports.
 5. A control valve as claimed in claim 4 in which said longitudinal passage means includes first and second longitudinal passages; one of said logic ports intercepts each of said longitudinal passages; said commutator port means includes a first commutator port intercepting said first longitudinal passage and a second commutator port intercepting said second longitudinal passage; and said commutator ports cooperate with said control port and adjacent portions of said spool bore to comprise said occluder means.
 6. A control valve as claimed in claim 5 in which movement of said valve spool from said neutral position toward one of said operating positions is effective to occlude communication between one of said commutator ports and said control port before said inlet port means is connected with one of said work ports.
 7. A control valve as claimed in claim 5 in which movement of said valve spool from said neutral position toward one of said operating positions is effective to occlude communication between one of said logic ports and one of said exhaust ports before said inlet port means is connected with one of said work ports.
 8. A control valve as claimed in claim 4 in which said occluder means includes fluid actuated valve means being adapted to communicate with said control port and with both of said longitudinal passages.
 9. A control valve as claimed in claim 8 in which said fluid actuated valve is comprised of a three-port logic valve having a first port in communication with said control port, a second port in communication with one of said logic ports, and a third port in communication with the other of said control ports; and said logic valve is effective to provide reversible flow fluid communication between said first port and one or the other of said ports at all times.
 10. A control valve as claimed in claim 4 in which movement of said valve spool from said neutral position toward one of said operating positions is effective to communicate one of said logic ports with one of said work ports before said inlet port means is connected with said one work port.
 11. A control valve as claimed in claim 4 in which said control valve includes first and second inlet port; and said work ports are interposed between said exhaust ports, said inlet ports are interposed between said work ports, and said control port is interposed between said inlet ports. 